Wireless communications, including radio frequency identification (RFID) and other near field communication (NFC) protocols, are gaining in popularity for applications such as security, inventory management, access control, and the like. The number of smart phones that include RFID or NFC protocols is growing along with the various applications of passive or active transponders, such as RFID circuits and NFC circuits. Such communications circuits may be coupled with an antenna that modulates, and in some instances emits, a wireless communication signal that can be read by a reader, such as a smartphone.
Electrochemical cells, or batteries, are commonly used as electrical energy sources. An electrochemical cell contains a negative electrode, typically called the anode, and a positive electrode, typically called the cathode. The anode contains an active material that can be oxidized. The cathode contains an active material that can be reduced. The anode active material is capable of reducing the cathode active material. A separator is disposed between the anode and cathode. An electrolyte is also included within the electrochemical cell. The aforementioned components are generally disposed in a can. A battery pack may include at least one electrochemical cell within a case. The battery pack may have specified external dimensions that, in part, limit the internal volume of the case available for the at least one electrochemical cell and other battery pack components.
Battery testers may be used to determine characteristics of a battery, or a battery pack, such as the remaining battery capacity. An exemplary type of a common battery tester that is placed on a battery is known as a thermochromic-type tester. In a thermochromic battery tester, a circuit may be completed by a consumer manually depressing one or two button switches. Once the circuit is completed, the consumer has electrically connected the battery to the thermochromic tester. The thermochromic tester may include a silver resistor, e.g., a flat silver layer that has a variable width so that the electrical resistance also varies along its length. As current travels through the silver resistor, the dissipated power generates heat that changes the color of a thermochromic ink display that is placed over the silver resistor. The thermochromic ink display may be arranged as a gauge to indicate the relative capacity of the battery. However, it is typically necessary for the consumer to inconveniently hold the battery and/or remove the battery from the device in order to test the battery using the battery tester.
Accordingly, there exists a need for a battery pack including an indicator circuit that does not require manual interaction between the consumer and the battery pack. In addition, the battery pack including an indicator circuit may also include advanced processing and communication capabilities. There also exists a need for a battery pack including an indicator circuit that does not detrimentally reduce the internal volume of the case that is available for the at least one electrochemical cell and other battery pack components.